Space and Physics
PUBLISHED
A PhD student from the University of Sydney has recreated "cosmic dust" in the laboratory, potentially making it much easier to study how the chemical building blocks of life may have formed, long before life existed on Earth.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.Cosmic dust – tiny grains of solid material floating through the cosmos – is a little hard to come by here on Earth. One source of it is to collect micrometeorites where they fall on Antarctica, or to collect these particles in the upper atmosphere.
"Since May 1981, the National Aeronautics and Space Administration (NASA) has used aircraft to collect cosmic dust (CD) particles from Earth's stratosphere," NASA explains. "Particles are individually retrieved from the collectors, examined and cataloged, and then made available to the scientific community for research."
Another way is to collect and analyze it on board spacecraft, such as Cassini's Cosmic Dust Analyzer, or targeted return missions, like NASA's often overlooked Stardust mission. Study of cosmic dust is pretty important to our understanding of life and the universe, given its role in it.
"Cosmic dust is essential to the function of the universe," NASA explains. "It shelters forming stars, becomes part of planets, and can contain the organic compounds that lead to life as we know it. Dust led to us."
Now, thanks to Linda Losurdo, a PhD candidate in materials and plasma physics in the School of Physics, we have a way to produce cosmic dust analogs in the laboratory. Losurdo used a mix of nitrogen, carbon dioxide, and acetylene gas in order to mimic environments found around stars and supernova remnants, before subjecting them to intense electrical energy. The result was carbon-rich grains, similar to real cosmic dust that drifts through the cosmos and is found inside comets and asteroids.
"Laboratory analogs are aids for understanding complex chemical environments that have the potential to form carbonaceous cosmic dust," the team explains in their study, adding that many previous studies have attempted to reproduce various properties of cosmic dust. "Fewer analog experiments incorporate the chemical complexity evident in solar system dust samples, such as the organic matter found in carbonaceous chondrites and comets."
Using a dielectric barrier discharge (DBD) plasma reactor, the team was able to synthesize a complex mix of carbon, hydrogen, oxygen and nitrogen which are essential for life, and known as CHON molecules.
"We no longer have to wait for an asteroid or comet to come to Earth to understand their histories," Losurdo said in a statement. "You can build analogue environments in the laboratory and reverse engineer their structure using the infrared fingerprints."
"This can give us huge insight into how 'carbonaceous cosmic dust' can form in the plasma puffed out by giant, old stars or in cosmic nurseries where stars are being born and distribute these fascinating molecules that could be vital for life. It's like we have recreated a little bit of the universe in a bottle in our lab."
As the mixture was subjected to 10,000 volts of electrical potential for an hour, molecules broke apart to form these more complex structures, before settling in a thin layer of dust. Looking at the spectra of the synthesized "cosmic dust", the team found that the analog dust gave off very similar spectra.
"By making cosmic dust in the lab, we can explore the intensity of ion impacts and temperatures involved when dust forms in space," Professor David McKenzie, co-author of the paper, added. "That's important if you want to understand the environments inside cosmic dust clouds, where life-relevant chemistry is thought to be happening."
"This also helps us interpret what a meteorite or asteroid fragment has been through over its lifetime. Its chemical signature holds a record of its journey, and experiments like this help us learn how to read that record."
The team plans to build a database of the spectra given off by lab-made "cosmic dust", which can then be compared to cosmic dust out there in the cosmos, to help us better understand its formation processes. Further study of cosmic dust could help inform us about the origins of life, and with cosmic dust analogs available in the lab, that task could get a little easier.
The study is published in The Astrophysical Journal.
